1. Field of the Invention
The present invention generally relates to hydrokinetic torque coupling devices, and more particularly to hydrokinetic torque coupling devices with a dynamic absorber for a torsional vibration damper.
2. Background of the Invention
An internal combustion engine exhibits irregularities due to the succession of combustion events in the engine cylinders. Torsional damping devices allow these irregularities to be filtered before the drive torque is transmitted to an automotive transmission. The vibrations preferably are damped before they enter the transmission and produce what may be considered unacceptably troublesome noise. To accomplish this, it is known to interpose a torsion damping device between a drive shaft and a transmission (or driven) shaft. The torsion damping device is typically arranged in a hydrokinetic torque coupling device that allows temporary rotational connection of the drive shaft to the transmission shaft.
Typically, a hydrokinetic torque coupling device includes a hydrodynamic torque converter and a torsion damping device positioned between an axially oriented coaxial drive shaft and a driven shaft of the automotive transmission. The torsion damping device includes a torque input element and a torque output element, and circumferentially acting elastic members. The circumferentially acting elastic members are interposed between the torque input element and the torque output element. In so-called “long travel” damping devices, the elastic members are mounted, in groups of at least two elastic members, in series between the input element and output element.
A torque converter of this kind typically has a rotating casing that is capable of transmitting drive torque to the damping device by means of a friction locking clutch, traditionally called a lock-up clutch. The torque converter also usually has a turbine wheel mounted rotatably inside the casing.
For some applications, the torsion damping device may also include a dynamic absorber having a heavy inertia member. A dynamic absorber having a heavy inertia member is arranged around the rotational axis of the engine shaft and is free to oscillate around an axis substantially parallel to the rotational axis of the engine shaft. The dynamic absorber is provided to lower a resonance frequency at low rotational speed of the engine and further improve the vibration damping performance.
While hydrokinetic torque coupling devices and torsion damping devices with dynamic absorbers, including but not limited to those discussed above, have proven to be acceptable for vehicular driveline applications and conditions, improvements that may enhance their performance and cost are possible.